包裝建議

種常用的存儲(chǔ)容器是瓦楞紙箱或木箱。除非它們被蠟涂層或樹(shù)脂處理過(guò)，否則水蒸氣很容易通過(guò)這些容器滲透。標(biāo)準(zhǔn)做法是使用塑料薄膜(如聚乙烯)對(duì)其進(jìn)行覆蓋。盡管這種塑料薄膜能夠阻隔液態(tài)水，但水蒸氣卻可能從中穿過(guò)。例如，1-mi聚乙烯的透水蒸氣速率約為1.5克平方英尺/24小時(shí)，而4mil聚乙烯在75°F和100%相對(duì)濕度下僅能透過(guò)約0.05克/平方英尺/24小時(shí)的量。我們通常建議您至少使用4密爾聚乙烯材料，或與之相當(dāng)?shù)钠渌牧希源_保其具備良好的水蒸氣透過(guò)率。

對(duì)于短期儲(chǔ)存——兩到四周——我們建議每20平方英尺4密爾聚乙烯使用8盎司DRIERITE，并補(bǔ)充足夠的DRIERITE以去除袋子或容器中水分。中期儲(chǔ)存（一到三個(gè)月）時(shí)，每塊10平方英尺的防潮層使用8盎司。如果是長(zhǎng)期儲(chǔ)存——三個(gè)月或更久——每五平方英尺的防潮層使用八盎司DRIERITE。在后面兩種情況下，必須加入足夠的額外的DRIERITE，以去除容器內(nèi)的水分。

上述推薦的DRIERITE劑量是基于相對(duì)穩(wěn)定的儲(chǔ)存條件得出的。如果存在較大的日溫差波動(dòng)或需應(yīng)對(duì)極端高溫與高濕度環(huán)境，則DRIERITE的用量應(yīng)加倍。

需要多少干燥劑？

密封容器或包裝內(nèi)水污染源有四種：包裝內(nèi)空氣中的水蒸氣、包裹內(nèi)材料中吸附的水、容器壁上的水，以及水蒸氣滲透到容器內(nèi)。為了保護(hù)容器或包裝內(nèi)的內(nèi)容物免受水的破壞，必須使用足夠的DRIERITE來(lái)去除這些水源中的全部水分。

密封容器在正常環(huán)境下密封，每10立方英尺的自由體積約需4盎司DRIERITE，以烘干容器內(nèi)空氣。在更極端的條件下（100°F和100% R.H.），需要8盎司的DRIERITE。容器里任何吸附著水的東西都需要額外的DRIERITE。木材和紙制品中吸附水量可達(dá)10%。泡沫塑料和某些橡膠制品的吸附水量可能僅為0.5%。一旦估算出容器中材料中的水分量，你可以通過(guò)將吸附水的重量除以0.06來(lái)計(jì)算出額外的DRIERITE量。保護(hù)密封容器所需的總DRIERITE量是干燥空氣體積所需的DRIERITE量與干燥容器內(nèi)材料所需DRIERITE量的總和。

如果使用密封良好的容器，如帶密封蓋的55加侖桶，所需DRIERITE的計(jì)算與密封容器相同，只是每10立方英尺體積額外加4盎司DRIERITE，以補(bǔ)償密封層的水分滲透。為了保護(hù)箱體，如保險(xiǎn)箱、工具箱或無(wú)墊圈的套筒，需要每5立方英尺體積約8盎司的DRIERITE，外加去除箱內(nèi)水分所需的DRIERITE。上述DRIERITE的數(shù)量基于環(huán)境儲(chǔ)存條件相對(duì)穩(wěn)定，且每日溫度波動(dòng)不大的假設(shè)。如果未密封容器存放在溫度每天波動(dòng)30華氏度的區(qū)域，該容器每月可能呼吸其自由體積的200%。如果是這樣，需要額外的DRIERITE來(lái)吸收因容器呼吸而進(jìn)入的水。

Packaging Suggestions

A commonly used storage container is a corrugated carton or a wooden box. Unless they are wax-coated or resin-treated, water vapor is transmitted through them quite readily. Standard practice is to line them with a plastic film, such as polyethylene. While the plastic film will hold liquid water, water vapor may pass through it. For instance, 1-mil polyethylene will pass water vapor at the rate of 1.5 grams/sq. ft./ 24 hrs, while 4-mil polyethylene will only pass about 0.05 grams/sq. ft./24 hrs at 75° F and 100% RH. We normally recommend that you use a minimum of 4-mil polyethylene, or something equivalent to it in water vapor transmission rate.

For short term storage - two to four weeks - we suggest that you use eight ounces of DRIERITE for every 20 sq. ft. of 4-mil polyethylene, plus sufficient DRIERITE to remove the water in the contents of the bag or container. For medium term storage - one to three months - use eight ounces for each 10 sq. ft. of vapor barrier. For long term storage - three months or longer - use eight ounces of DRIERITE for every five square feet of vapor barrier. Enough extra DRIERITE will have to be added in the last two cases to remove the water in the contents of the container.

The quantities of DRIERITE recommended above are based on relatively stable storage conditions. If there are large daily fluctuations in temperature or if extremely high temperatures and high humidity are to be encountered, the amount of DRIERITE should be doubled.

How Much DRIERITE Is Required?

There are four sources of water contamination in a closed container or package: the water vapor in the air inside the package, the water adsorbed in the materials inside the package, the water adsorbed on the walls of the container, and the permeation of water vapor into the container. In order to protect the contents of a container or package from the destructive effects of water, enough DRIERITE must be used to remove all the water from these sources.

A hermetically sealed container, closed in a normal ambient atmosphere, would require approximately four ounces of DRIERITE for every 10 cubic feet of free volume to dry the air in the container. At more extreme conditions (100° F and 100% R.H.) eight ounces of DRIERITE would be required. Anything in the container that has water adsorbed in it would require extra DRIERITE. Wood and paper products can have as much as 10% by weight adsorbed water. Styrofoam and some rubber products may have as little as 0.5% adsorbed water. Once the amount of water in the material in the container has been estimated, you can calculate the amount of extra DRIERITE required by dividing the weight of the adsorbed water by 0.06. The total amount of DRIERITE required to protect a hermetically sealed container would be the sum of the amount of DRIERITE required to dry the air volume plus the amount of DRIERITE required to dry the materials in the container.

If a well-sealed container, such as a 55 gallon drum with a gasketed lid, is being used, the amount of DRIERITE required is calculated the same as for a hermetically sealed container, except that an additional four ounces of DRIERITE per ten cubic feet of volume is used to compensate for moisture permeation through the seal. To protect an enclosure such as a safe, tool box or a slip cover can, where there is no gasket, requires about eight ounces of DRIERITE per five cubic feet of volume plus the DRIERITE required to remove the water from the contents of the enclosure. The quantities of DRIERITE suggested above are predicated on the assumption that the ambient storage conditions are rather stable, and there are not large temperature fluctuations daily. If an unsealed container were stored in a area where the temperature could fluctuate 30° F daily, the container may possibly breathe 200% of its free volume per month. If this were the case, additional DRIERITE would be needed to absorb the water entering due to the breathing of the container.